This invention relates to bar attachment systems for attaching implants to dentures.
Implants in the jawbone often act as anchor points for dental prosthetic devices such as crowns, bridges, and partial and full dentures. In upper dentures, and often in lower dentures, several implants are splinted together by a bar, and the bar is connected in turn to the denture. This provides better support for the denture and distributes load more evenly. This is particularly important in the upper jaw where the bone is less dense. Use of a bar also retains the denture attachment fixtures parallel to one another, making insertion and removal easier. Conventional bars typically attach to the implants by means of screws at the ends of the bar. The bar has upwardly projecting balls or horizontal bars for snap engagement with a cooperating socket in the denture.
One problem with existing bar attachments is that they have a relatively high profile, due to the balls or bars which project up above the bar. This makes the bar uncomfortable to the patient when the denture is removed for cleaning or overnight. It also takes up room in providing the socket space in the denture itself.
Another problem is the lateral torque produced due to the offset between the denture attachment points and the implant attachment points. This produces a cantilever effect which may tend to loosen the implant. Additionally, where implants are located close together, as is normal due to the fact that implants can normally only be placed in anterior regions of the mouth to reduce the risk of contact with the nerve, there is little space left for providing the denture attachment balls or bars. Conventional bars also cannot be secured over highly divergent implants. Proper fitting is another problem with existing bar systems, which often need to be repeatedly cut and re-soldered due to poor initial fitting.